1. Field of the Invention
The present invention relates to run-away preventive arrangements for vehicles, such as snowmobiles or other motorized devices.
2. Prior Art
In the prior art, so called "dead man" controls or run away preventing systems have been advanced for many different types of devices. In the U.S. Pat. No. 3,849,620 to Melisz a control which uses two series connected switches, one operated by a separate "dead man" lever on the handle of a power trowel and the other near the throttle control lever on the handle does have two normally closed switches in series that will ground the ignition if both are closed. The unit requires two separate hand actuated levers, one a dead man control, and the other the manual operated throttle control, and does not have a separately controlled switch on the carburetor itself. Also, it must be pointed out that in the device shown in the Melisz patent freezing or binding of the pivot pin for the dead man control can cause malfunction of the safety system, because of the placement of the switches.
U.S. Pat. No. 3,789,938, issued to Hetteen shows a switch arrangement for providing a safety shut off for a snowmobile, but the switches are in parallel. In this particular device, one of the switches is positioned at the throttle arm and it appears that the throttle arm forms one of the contacts of the switch of the carburetor.
The Filip U.S. Pat. No. 3,881,461 shows an automatic cut-off device for vehicles, where two switches have to be operated in sequential operation, and the switches are located in only one location, so that the necessary safety under potential adverse conditions such as the seizing of a throttle control rod, or of the throttle arm would not provide for the desired safety features.
Another type of control, different than the present invention, is illustrated in the Veilleux U.S. Pat. No. 3,695,379. This device, which relates to ignition systems of automobiles is not concerned directly with hand throttle controls, and includes a panic button for stopping the engine.
Other devices uncovered in the preliminary search in this case which generally show the state of the art, include the following U.S. Pat. Nos. 2,550,999 -- Hoffman, 3,791,366 -- MacMillan, 3,789,402 -- Raab, 3,734,230 -- Tanaka, 3,672,344 -- Albertson, 3,758,736 -- Tanaka, 3,845,847 -- Camp, 3,303,836 -- Burleigh, 2,296,003 -- Van Loo, 3,742,928 -- Albertson.